Mobile communication devices are increasingly common, particularly in metropolitan regions of the world. These devices have evolved from simple radio telephones to complex, multi-mode devices that may incorporate computing ability for executing applications and programs. Manufacturers have endeavored to include increased functionality in smaller volume while reducing power consumption to increase operation time for a given battery capacity.
The communications landscape has evolved as well, and there are now a variety of competing communications systems, protocols, and air interfaces offered in the marketplace. There are also different modes of communication and services available. Some manufacturers, rather than design mobile communication devices that only operate with one type of air interface and only offer one communication mode, are designing multi-mode communication devices that can access more than one type of communication system and communicate using more than one mode of communication.
In order to keep with goals of small size, weight, and low power consumption, however, manufacturers have had to design circuitry such that it can be used in as many of the different modes as possible. The fact that communication is now almost entirely digital allows much of the signal processing to be performed by processors, such as digital signal processor, according to instruction code. However, certain elements are difficult to share across different communication schemes. For example, a transmitter designed for amplitude modulation may not be a likely candidate for use with a communication protocol calling for angle modulation with a constant envelope. Typically for multi-mode devices using such diverse communication protocols manufacturers have been forced to use separate transmitters for each modulation form. This is undesirable because transmitter components may be among the more costly components in the design of a communications device. Therefore there is a need for transmitter that can support multiple communication schemes having diverse modulations schemes.